144,000 has come to signify to me the completed church, though it may have literal overtones as well. Both the redeemed company standing with The Lamb, singing the New Song, and the 'measurement' of the wall of the New Jerusalem have signified that to me for 20 years.
I merely follow other contributors in observing:
Today , May 14th, 400 years ago, 144 men and boys (settlers + sailors) landed at Jamestown after a voyage of 144 days from England. Though a commercial settlement enterprise from the 'Virginia Company' they carried instruction (confirmed by King George) to spread the Christian gospel, in the hands of faithful preachers, and God was listening - hence the USA. Faithful pilgrims were to follow that first and significant step.
(Genesis 15v13 prophecies that Abraham's descendants would live as stranger/pilgrims for 400 years, before 'coming out' to receive the inheritance. Fulfilled first in Egypt.)
Today I read the population figures, released yesterday, from Jerusalem. The population of Jerusalem is 720,000 = 144,000 times 5. (That's also the number of days in 2000 years ('2 days'?) of 360 days, such as you would find in the prophecies of Revelation and Daniel)
Wednesday is 'Jerusalem Day' - 40 years after its reunification.
Thursday is Ascension day, 40 days after the Resurrection.
I'm no mathematician, but there's a lot of mighty significant numbers around this week!
(You can check my statistics by Googling them)
PS I'm not an American!